The present invention relates to a method for transformation of a microorganism and more specifically to a method whereby DNA such as a plasmid is introduced into a microorganism belonging to the genus Corynebacterium or Brevibacterium.
Recently, considerable attention has been devoted to genetic engineering technology wherein foreign genes are recombined with a vector DNA in vitro and the recombinant DNA is introduced into host cells. Such transformants are important as a means to produce the foreign DNA by autonomous replication of the vector and to endow the cell with valuable properties due to the presence of the foreign DNA.
Although most studies in this art have been developed using Escherichia coli as a host, efforts to establish recombinant DNA technology have been attempted on industrially useful microorganisms such as amylase-producing Bacillus subtilis, antibiotic-producing Actinomycetes and alcohol-producing yeasts. Recombinant DNA technology in any of the species of microorganisms requires essentially a vector, such as plasmids and phages, which can replicate autonomously in cells and a transformation method to introduce a recombinant DNA of the vector and a foreign DNA into the host cell. An applicable transformation method is, of course, a particularly important aspect for genetic engineering of industrially useful microorganisms such as those belonging to the genera Corynebacterium and Brevibacterium which are in use for the production of commercially significant products, for example glutamic acid, lysine and the like. To this end, a transformation method has now been developed suitable for microorganisms belonging to the genera Corynebacterium and Brevibacterium using the plasmid pCG4, isolated from Corynebacterium glutamicum 225-250, as a vector. The transformation procedure is, however, applicable to any plasmid and phage system.
Thus, the present invention provides a standard technique which enables the application of recombinant DNA technology to microorganisms belonging to the genus Corynebacterium or Brevibacterium, that is, to clone a desired gene of homologous or foreign origin.